Best Leappad apps?

For those of you with kids who have (or had) Leappads recently, what are their favorite games or apps?
 
We are getting our boys each a Leappad for Christmas.  We plan to download about 3-4 games or things (like eBooks), and then since they have a birthday 3 days after Christmas, we are putting some games and download gift cards on their wish list, and we will probably let them each pick 1-2 more.
 
I looked online and there are TONS of videos - I don't care too much about those because they have lots of movies, we DVR things, etc.  So mostly I want to focus on games and eBooks I think.